/*****************************************************************************
* fsm.c - Network Control Protocol Finite State Machine program file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* portions Copyright (c) 1997 by Global Election Systems Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <marc@mbsi.ca>
*   Ported to lwIP.
* 97-12-01 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
*   Original based on BSD fsm.c.
*****************************************************************************/
/*
 * fsm.c - {Link, IP} Control Protocol Finite State Machine.
 *
 * Copyright (c) 1989 Carnegie Mellon University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Carnegie Mellon University.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 * TODO:
 * Randomize fsm id on link/init.
 * Deal with variable outgoing MTU.
 */

#include "lwip/opt.h"

#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#include "ppp.h"
#include "pppdebug.h"

#include "fsm.h"

#include <string.h>


/*************************/
/*** LOCAL DEFINITIONS ***/
/*************************/

#if PPP_DEBUG

static const char *ppperr_strerr[] = {
    "LS_INITIAL",         /* LS_INITIAL  0 */
    "LS_STARTING",        /* LS_STARTING 1 */
    "LS_CLOSED",          /* LS_CLOSED   2 */
    "LS_STOPPED",         /* LS_STOPPED  3 */
    "LS_CLOSING",         /* LS_CLOSING  4 */
    "LS_STOPPING",        /* LS_STOPPING 5 */
    "LS_REQSENT",         /* LS_REQSENT  6 */
    "LS_ACKRCVD",         /* LS_ACKRCVD  7 */
    "LS_ACKSENT",         /* LS_ACKSENT  8 */
    "LS_OPENED"           /* LS_OPENED   9 */
};

#endif /* PPP_DEBUG */

/************************/
/*** LOCAL DATA TYPES ***/
/************************/


/***********************************/
/*** LOCAL FUNCTION DECLARATIONS ***/
/***********************************/
static void fsm_timeout(void *);
static void fsm_rconfreq(fsm *, u_char, u_char *, int);
static void fsm_rconfack(fsm *, int, u_char *, int);
static void fsm_rconfnakrej(fsm *, int, int, u_char *, int);
static void fsm_rtermreq(fsm *, int, u_char *, int);
static void fsm_rtermack(fsm *);
static void fsm_rcoderej(fsm *, u_char *, int);
static void fsm_sconfreq(fsm *, int);

#define PROTO_NAME(f) ((f)->callbacks->proto_name)


/******************************/
/*** PUBLIC DATA STRUCTURES ***/
/******************************/


/*****************************/
/*** LOCAL DATA STRUCTURES ***/
/*****************************/
int peer_mru[NUM_PPP];


/***********************************/
/*** PUBLIC FUNCTION DEFINITIONS ***/
/***********************************/

/*
 * fsm_init - Initialize fsm.
 *
 * Initialize fsm state.
 */
void
fsm_init(fsm *f)
{
    f->state = LS_INITIAL;
    f->flags = 0;
    f->id = 0;      /* XXX Start with random id? */
    f->timeouttime = FSM_DEFTIMEOUT;
    f->maxconfreqtransmits = FSM_DEFMAXCONFREQS;
    f->maxtermtransmits = FSM_DEFMAXTERMREQS;
    f->maxnakloops = FSM_DEFMAXNAKLOOPS;
    f->term_reason_len = 0;
}


/*
 * fsm_lowerup - The lower layer is up.
 */
void
fsm_lowerup(fsm *f)
{
    int oldState = f->state;

    LWIP_UNUSED_ARG(oldState);

    switch ( f->state )
    {
    case LS_INITIAL:
        f->state = LS_CLOSED;
        break;

    case LS_STARTING:
        if ( f->flags & OPT_SILENT )
        {
            f->state = LS_STOPPED;
        }
        else
        {
            /* Send an initial configure-request */
            fsm_sconfreq(f, 0);
            f->state = LS_REQSENT;
        }
        break;

    default:
        FSMDEBUG((LOG_INFO, "%s: Up event in state %d (%s)!\n",
                  PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
    }

    FSMDEBUG((LOG_INFO, "%s: lowerup state %d (%s) -> %d (%s)\n",
              PROTO_NAME(f), oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));
}


/*
 * fsm_lowerdown - The lower layer is down.
 *
 * Cancel all timeouts and inform upper layers.
 */
void
fsm_lowerdown(fsm *f)
{
    int oldState = f->state;

    LWIP_UNUSED_ARG(oldState);

    switch ( f->state )
    {
    case LS_CLOSED:
        f->state = LS_INITIAL;
        break;

    case LS_STOPPED:
        f->state = LS_STARTING;
        if ( f->callbacks->starting )
        {
            (*f->callbacks->starting)(f);
        }
        break;

    case LS_CLOSING:
        f->state = LS_INITIAL;
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
        break;

    case LS_STOPPING:
    case LS_REQSENT:
    case LS_ACKRCVD:
    case LS_ACKSENT:
        f->state = LS_STARTING;
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
        break;

    case LS_OPENED:
        if ( f->callbacks->down )
        {
            (*f->callbacks->down)(f);
        }
        f->state = LS_STARTING;
        break;

    default:
        FSMDEBUG((LOG_INFO, "%s: Down event in state %d (%s)!\n",
                  PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
    }

    FSMDEBUG((LOG_INFO, "%s: lowerdown state %d (%s) -> %d (%s)\n",
              PROTO_NAME(f), oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));
}


/*
 * fsm_open - Link is allowed to come up.
 */
void
fsm_open(fsm *f)
{
    int oldState = f->state;

    LWIP_UNUSED_ARG(oldState);

    switch ( f->state )
    {
    case LS_INITIAL:
        f->state = LS_STARTING;
        if ( f->callbacks->starting )
        {
            (*f->callbacks->starting)(f);
        }
        break;

    case LS_CLOSED:
        if ( f->flags & OPT_SILENT )
        {
            f->state = LS_STOPPED;
        }
        else
        {
            /* Send an initial configure-request */
            fsm_sconfreq(f, 0);
            f->state = LS_REQSENT;
        }
        break;

    case LS_CLOSING:
        f->state = LS_STOPPING;
    /* fall through */
    case LS_STOPPED:
    case LS_OPENED:
        if ( f->flags & OPT_RESTART )
        {
            fsm_lowerdown(f);
            fsm_lowerup(f);
        }
        break;
    }

    FSMDEBUG((LOG_INFO, "%s: open state %d (%s) -> %d (%s)\n",
              PROTO_NAME(f), oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));
}


/*
 * fsm_close - Start closing connection.
 *
 * Cancel timeouts and either initiate close or possibly go directly to
 * the LS_CLOSED state.
 */
void
fsm_close(fsm *f, char *reason)
{
    int oldState = f->state;

    LWIP_UNUSED_ARG(oldState);

    f->term_reason = reason;
    f->term_reason_len = (reason == NULL ? 0 : strlen(reason));
    switch ( f->state )
    {
    case LS_STARTING:
        f->state = LS_INITIAL;
        break;
    case LS_STOPPED:
        f->state = LS_CLOSED;
        break;
    case LS_STOPPING:
        f->state = LS_CLOSING;
        break;

    case LS_REQSENT:
    case LS_ACKRCVD:
    case LS_ACKSENT:
    case LS_OPENED:
        if ( f->state != LS_OPENED )
        {
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
        }
        else if ( f->callbacks->down )
        {
            (*f->callbacks->down)(f); /* Inform upper layers we're down */
        }
        /* Init restart counter, send Terminate-Request */
        f->retransmits = f->maxtermtransmits;
        fsm_sdata(f, TERMREQ, f->reqid = ++f->id,
                  (u_char*)f->term_reason, f->term_reason_len);
        TIMEOUT(fsm_timeout, f, f->timeouttime);
        --f->retransmits;

        f->state = LS_CLOSING;
        break;
    }

    FSMDEBUG((LOG_INFO, "%s: close reason=%s state %d (%s) -> %d (%s)\n",
              PROTO_NAME(f), reason, oldState, ppperr_strerr[oldState], f->state, ppperr_strerr[f->state]));
}


/*
 * fsm_sdata - Send some data.
 *
 * Used for all packets sent to our peer by this module.
 */
void
fsm_sdata( fsm *f, u_char code, u_char id, u_char *data, int datalen)
{
    u_char *outp;
    int outlen;

    /* Adjust length to be smaller than MTU */
    outp = outpacket_buf[f->unit];
    if (datalen > peer_mru[f->unit] - (int)HEADERLEN)
    {
        datalen = peer_mru[f->unit] - HEADERLEN;
    }
    if (datalen && data != outp + PPP_HDRLEN + HEADERLEN)
    {
        BCOPY(data, outp + PPP_HDRLEN + HEADERLEN, datalen);
    }
    outlen = datalen + HEADERLEN;
    MAKEHEADER(outp, f->protocol);
    PUTCHAR(code, outp);
    PUTCHAR(id, outp);
    PUTSHORT(outlen, outp);
    pppWrite(f->unit, outpacket_buf[f->unit], outlen + PPP_HDRLEN);
    FSMDEBUG((LOG_INFO, "fsm_sdata(%s): Sent code %d,%d,%d.\n",
              PROTO_NAME(f), code, id, outlen));
}


/*
 * fsm_input - Input packet.
 */
void
fsm_input(fsm *f, u_char *inpacket, int l)
{
    u_char *inp = inpacket;
    u_char code, id;
    int len;

    /*
     * Parse header (code, id and length).
     * If packet too short, drop it.
     */
    if (l < HEADERLEN)
    {
        FSMDEBUG((LOG_WARNING, "fsm_input(%x): Rcvd short header.\n",
                  f->protocol));
        return;
    }
    GETCHAR(code, inp);
    GETCHAR(id, inp);
    GETSHORT(len, inp);
    if (len < HEADERLEN)
    {
        FSMDEBUG((LOG_INFO, "fsm_input(%x): Rcvd illegal length.\n",
                  f->protocol));
        return;
    }
    if (len > l)
    {
        FSMDEBUG((LOG_INFO, "fsm_input(%x): Rcvd short packet.\n",
                  f->protocol));
        return;
    }
    len -= HEADERLEN;  /* subtract header length */

    if ( f->state == LS_INITIAL || f->state == LS_STARTING )
    {
        FSMDEBUG((LOG_INFO, "fsm_input(%x): Rcvd packet in state %d (%s).\n",
                  f->protocol, f->state, ppperr_strerr[f->state]));
        return;
    }
    FSMDEBUG((LOG_INFO, "fsm_input(%s):%d,%d,%d\n", PROTO_NAME(f), code, id, l));
    /*
     * Action depends on code.
     */
    switch (code)
    {
    case CONFREQ:
        fsm_rconfreq(f, id, inp, len);
        break;

    case CONFACK:
        fsm_rconfack(f, id, inp, len);
        break;

    case CONFNAK:
    case CONFREJ:
        fsm_rconfnakrej(f, code, id, inp, len);
        break;

    case TERMREQ:
        fsm_rtermreq(f, id, inp, len);
        break;

    case TERMACK:
        fsm_rtermack(f);
        break;

    case CODEREJ:
        fsm_rcoderej(f, inp, len);
        break;

    default:
        if ( !f->callbacks->extcode ||
             !(*f->callbacks->extcode)(f, code, id, inp, len) )
        {
            fsm_sdata(f, CODEREJ, ++f->id, inpacket, len + HEADERLEN);
        }
        break;
    }
}


/*
 * fsm_protreject - Peer doesn't speak this protocol.
 *
 * Treat this as a catastrophic error (RXJ-).
 */
void
fsm_protreject(fsm *f)
{
    switch ( f->state )
    {
    case LS_CLOSING:
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
    /* fall through */
    case LS_CLOSED:
        f->state = LS_CLOSED;
        if ( f->callbacks->finished )
        {
            (*f->callbacks->finished)(f);
        }
        break;

    case LS_STOPPING:
    case LS_REQSENT:
    case LS_ACKRCVD:
    case LS_ACKSENT:
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
    /* fall through */
    case LS_STOPPED:
        f->state = LS_STOPPED;
        if ( f->callbacks->finished )
        {
            (*f->callbacks->finished)(f);
        }
        break;

    case LS_OPENED:
        if ( f->callbacks->down )
        {
            (*f->callbacks->down)(f);
        }
        /* Init restart counter, send Terminate-Request */
        f->retransmits = f->maxtermtransmits;
        fsm_sdata(f, TERMREQ, f->reqid = ++f->id,
                  (u_char*)f->term_reason, f->term_reason_len);
        TIMEOUT(fsm_timeout, f, f->timeouttime);
        --f->retransmits;

        f->state = LS_STOPPING;
        break;

    default:
        FSMDEBUG((LOG_INFO, "%s: Protocol-reject event in state %d (%s)!\n",
                  PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
    }
}





/**********************************/
/*** LOCAL FUNCTION DEFINITIONS ***/
/**********************************/

/*
 * fsm_timeout - Timeout expired.
 */
static void
fsm_timeout(void *arg)
{
    fsm *f = (fsm*)arg;

    switch (f->state)
    {
    case LS_CLOSING:
    case LS_STOPPING:
        if ( f->retransmits <= 0 )
        {
            FSMDEBUG((LOG_WARNING, "%s: timeout sending Terminate-Request state=%d (%s)\n",
                      PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
            /*
             * We've waited for an ack long enough.  Peer probably heard us.
             */
            f->state = (f->state == LS_CLOSING) ? LS_CLOSED : LS_STOPPED;
            if ( f->callbacks->finished )
            {
                (*f->callbacks->finished)(f);
            }
        }
        else
        {
            FSMDEBUG((LOG_WARNING, "%s: timeout resending Terminate-Requests state=%d (%s)\n",
                      PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
            /* Send Terminate-Request */
            fsm_sdata(f, TERMREQ, f->reqid = ++f->id,
                      (u_char*)f->term_reason, f->term_reason_len);
            TIMEOUT(fsm_timeout, f, f->timeouttime);
            --f->retransmits;
        }
        break;

    case LS_REQSENT:
    case LS_ACKRCVD:
    case LS_ACKSENT:
        if (f->retransmits <= 0)
        {
            FSMDEBUG((LOG_WARNING, "%s: timeout sending Config-Requests state=%d (%s)\n",
                      PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
            f->state = LS_STOPPED;
            if ( (f->flags & OPT_PASSIVE) == 0 && f->callbacks->finished )
            {
                (*f->callbacks->finished)(f);
            }
        }
        else
        {
            FSMDEBUG((LOG_WARNING, "%s: timeout resending Config-Request state=%d (%s)\n",
                      PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
            /* Retransmit the configure-request */
            if (f->callbacks->retransmit)
            {
                (*f->callbacks->retransmit)(f);
            }
            fsm_sconfreq(f, 1); /* Re-send Configure-Request */
            if ( f->state == LS_ACKRCVD )
            {
                f->state = LS_REQSENT;
            }
        }
        break;

    default:
        FSMDEBUG((LOG_INFO, "%s: UNHANDLED timeout event in state %d (%s)!\n",
                  PROTO_NAME(f), f->state, ppperr_strerr[f->state]));
    }
}


/*
 * fsm_rconfreq - Receive Configure-Request.
 */
static void
fsm_rconfreq(fsm *f, u_char id, u_char *inp, int len)
{
    int code, reject_if_disagree;

    FSMDEBUG((LOG_INFO, "fsm_rconfreq(%s): Rcvd id %d state=%d (%s)\n",
              PROTO_NAME(f), id, f->state, ppperr_strerr[f->state]));
    switch ( f->state )
    {
    case LS_CLOSED:
        /* Go away, we're closed */
        fsm_sdata(f, TERMACK, id, NULL, 0);
        return;
    case LS_CLOSING:
    case LS_STOPPING:
        return;

    case LS_OPENED:
        /* Go down and restart negotiation */
        if ( f->callbacks->down )
        {
            (*f->callbacks->down)(f); /* Inform upper layers */
        }
        fsm_sconfreq(f, 0);  /* Send initial Configure-Request */
        break;

    case LS_STOPPED:
        /* Negotiation started by our peer */
        fsm_sconfreq(f, 0);  /* Send initial Configure-Request */
        f->state = LS_REQSENT;
        break;
    }

    /*
     * Pass the requested configuration options
     * to protocol-specific code for checking.
     */
    if (f->callbacks->reqci)    /* Check CI */
    {
        reject_if_disagree = (f->nakloops >= f->maxnakloops);
        code = (*f->callbacks->reqci)(f, inp, &len, reject_if_disagree);
    }
    else if (len)
    {
        code = CONFREJ;  /* Reject all CI */
    }
    else
    {
        code = CONFACK;
    }

    /* send the Ack, Nak or Rej to the peer */
    fsm_sdata(f, (u_char)code, id, inp, len);

    if (code == CONFACK)
    {
        if (f->state == LS_ACKRCVD)
        {
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
            f->state = LS_OPENED;
            if (f->callbacks->up)
            {
                (*f->callbacks->up)(f); /* Inform upper layers */
            }
        }
        else
        {
            f->state = LS_ACKSENT;
        }
        f->nakloops = 0;
    }
    else
    {
        /* we sent CONFACK or CONFREJ */
        if (f->state != LS_ACKRCVD)
        {
            f->state = LS_REQSENT;
        }
        if ( code == CONFNAK )
        {
            ++f->nakloops;
        }
    }
}


/*
 * fsm_rconfack - Receive Configure-Ack.
 */
static void
fsm_rconfack(fsm *f, int id, u_char *inp, int len)
{
    FSMDEBUG((LOG_INFO, "fsm_rconfack(%s): Rcvd id %d state=%d (%s)\n",
              PROTO_NAME(f), id, f->state, ppperr_strerr[f->state]));

    if (id != f->reqid || f->seen_ack)   /* Expected id? */
    {
        return; /* Nope, toss... */
    }
    if ( !(f->callbacks->ackci ? (*f->callbacks->ackci)(f, inp, len) : (len == 0)) )
    {
        /* Ack is bad - ignore it */
        FSMDEBUG((LOG_INFO, "%s: received bad Ack (length %d)\n",
                  PROTO_NAME(f), len));
        return;
    }
    f->seen_ack = 1;

    switch (f->state)
    {
    case LS_CLOSED:
    case LS_STOPPED:
        fsm_sdata(f, TERMACK, (u_char)id, NULL, 0);
        break;

    case LS_REQSENT:
        f->state = LS_ACKRCVD;
        f->retransmits = f->maxconfreqtransmits;
        break;

    case LS_ACKRCVD:
        /* Huh? an extra valid Ack? oh well... */
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
        fsm_sconfreq(f, 0);
        f->state = LS_REQSENT;
        break;

    case LS_ACKSENT:
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
        f->state = LS_OPENED;
        f->retransmits = f->maxconfreqtransmits;
        if (f->callbacks->up)
        {
            (*f->callbacks->up)(f); /* Inform upper layers */
        }
        break;

    case LS_OPENED:
        /* Go down and restart negotiation */
        if (f->callbacks->down)
        {
            (*f->callbacks->down)(f); /* Inform upper layers */
        }
        fsm_sconfreq(f, 0);  /* Send initial Configure-Request */
        f->state = LS_REQSENT;
        break;
    }
}


/*
 * fsm_rconfnakrej - Receive Configure-Nak or Configure-Reject.
 */
static void
fsm_rconfnakrej(fsm *f, int code, int id, u_char *inp, int len)
{
    int (*proc) (fsm *, u_char *, int);
    int ret;

    FSMDEBUG((LOG_INFO, "fsm_rconfnakrej(%s): Rcvd id %d state=%d (%s)\n",
              PROTO_NAME(f), id, f->state, ppperr_strerr[f->state]));

    if (id != f->reqid || f->seen_ack) /* Expected id? */
    {
        return;    /* Nope, toss... */
    }
    proc = (code == CONFNAK) ? f->callbacks->nakci : f->callbacks->rejci;
    if (!proc || !((ret = proc(f, inp, len))))
    {
        /* Nak/reject is bad - ignore it */
        FSMDEBUG((LOG_INFO, "%s: received bad %s (length %d)\n",
                  PROTO_NAME(f), (code == CONFNAK ? "Nak" : "reject"), len));
        return;
    }
    f->seen_ack = 1;

    switch (f->state)
    {
    case LS_CLOSED:
    case LS_STOPPED:
        fsm_sdata(f, TERMACK, (u_char)id, NULL, 0);
        break;

    case LS_REQSENT:
    case LS_ACKSENT:
        /* They didn't agree to what we wanted - try another request */
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
        if (ret < 0)
        {
            f->state = LS_STOPPED; /* kludge for stopping CCP */
        }
        else
        {
            fsm_sconfreq(f, 0); /* Send Configure-Request */
        }
        break;

    case LS_ACKRCVD:
        /* Got a Nak/reject when we had already had an Ack?? oh well... */
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
        fsm_sconfreq(f, 0);
        f->state = LS_REQSENT;
        break;

    case LS_OPENED:
        /* Go down and restart negotiation */
        if (f->callbacks->down)
        {
            (*f->callbacks->down)(f); /* Inform upper layers */
        }
        fsm_sconfreq(f, 0);  /* Send initial Configure-Request */
        f->state = LS_REQSENT;
        break;
    }
}


/*
 * fsm_rtermreq - Receive Terminate-Req.
 */
static void
fsm_rtermreq(fsm *f, int id, u_char *p, int len)
{
    LWIP_UNUSED_ARG(p);

    FSMDEBUG((LOG_INFO, "fsm_rtermreq(%s): Rcvd id %d state=%d (%s)\n",
              PROTO_NAME(f), id, f->state, ppperr_strerr[f->state]));

    switch (f->state)
    {
    case LS_ACKRCVD:
    case LS_ACKSENT:
        f->state = LS_REQSENT;  /* Start over but keep trying */
        break;

    case LS_OPENED:
        if (len > 0)
        {
            FSMDEBUG((LOG_INFO, "%s terminated by peer (%x)\n", PROTO_NAME(f), p));
        }
        else
        {
            FSMDEBUG((LOG_INFO, "%s terminated by peer\n", PROTO_NAME(f)));
        }
        if (f->callbacks->down)
        {
            (*f->callbacks->down)(f); /* Inform upper layers */
        }
        f->retransmits = 0;
        f->state = LS_STOPPING;
        TIMEOUT(fsm_timeout, f, f->timeouttime);
        break;
    }

    fsm_sdata(f, TERMACK, (u_char)id, NULL, 0);
}


/*
 * fsm_rtermack - Receive Terminate-Ack.
 */
static void
fsm_rtermack(fsm *f)
{
    FSMDEBUG((LOG_INFO, "fsm_rtermack(%s): state=%d (%s)\n",
              PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

    switch (f->state)
    {
    case LS_CLOSING:
        UNTIMEOUT(fsm_timeout, f);
        f->state = LS_CLOSED;
        if ( f->callbacks->finished )
        {
            (*f->callbacks->finished)(f);
        }
        break;

    case LS_STOPPING:
        UNTIMEOUT(fsm_timeout, f);
        f->state = LS_STOPPED;
        if ( f->callbacks->finished )
        {
            (*f->callbacks->finished)(f);
        }
        break;

    case LS_ACKRCVD:
        f->state = LS_REQSENT;
        break;

    case LS_OPENED:
        if (f->callbacks->down)
        {
            (*f->callbacks->down)(f); /* Inform upper layers */
        }
        fsm_sconfreq(f, 0);
        break;
    }
}


/*
 * fsm_rcoderej - Receive an Code-Reject.
 */
static void
fsm_rcoderej(fsm *f, u_char *inp, int len)
{
    u_char code, id;

    FSMDEBUG((LOG_INFO, "fsm_rcoderej(%s): state=%d (%s)\n",
              PROTO_NAME(f), f->state, ppperr_strerr[f->state]));

    if (len < HEADERLEN)
    {
        FSMDEBUG((LOG_INFO, "fsm_rcoderej: Rcvd short Code-Reject packet!\n"));
        return;
    }
    GETCHAR(code, inp);
    GETCHAR(id, inp);
    FSMDEBUG((LOG_WARNING, "%s: Rcvd Code-Reject for code %d, id %d\n",
              PROTO_NAME(f), code, id));

    if ( f->state == LS_ACKRCVD )
    {
        f->state = LS_REQSENT;
    }
}


/*
 * fsm_sconfreq - Send a Configure-Request.
 */
static void
fsm_sconfreq(fsm *f, int retransmit)
{
    u_char *outp;
    int cilen;

    if ( f->state != LS_REQSENT && f->state != LS_ACKRCVD && f->state != LS_ACKSENT )
    {
        /* Not currently negotiating - reset options */
        if ( f->callbacks->resetci )
        {
            (*f->callbacks->resetci)(f);
        }
        f->nakloops = 0;
    }

    if ( !retransmit )
    {
        /* New request - reset retransmission counter, use new ID */
        f->retransmits = f->maxconfreqtransmits;
        f->reqid = ++f->id;
    }

    f->seen_ack = 0;

    /*
     * Make up the request packet
     */
    outp = outpacket_buf[f->unit] + PPP_HDRLEN + HEADERLEN;
    if ( f->callbacks->cilen && f->callbacks->addci )
    {
        cilen = (*f->callbacks->cilen)(f);
        if ( cilen > peer_mru[f->unit] - (int)HEADERLEN )
        {
            cilen = peer_mru[f->unit] - HEADERLEN;
        }
        if (f->callbacks->addci)
        {
            (*f->callbacks->addci)(f, outp, &cilen);
        }
    }
    else
    {
        cilen = 0;
    }

    /* send the request to our peer */
    fsm_sdata(f, CONFREQ, f->reqid, outp, cilen);

    /* start the retransmit timer */
    --f->retransmits;
    TIMEOUT(fsm_timeout, f, f->timeouttime);

    FSMDEBUG((LOG_INFO, "%s: sending Configure-Request, id %d\n",
              PROTO_NAME(f), f->reqid));
}

#endif /* PPP_SUPPORT */
